1. Field of the invention
This invention relates to a package for testing unpackaged or bare die and in one aspect relates to a carrier for positioning the bare die to make electrical contact therewith and to the outside of the package to permit electrical testing and burn-in.
1. Background of the Invention
Semi-conductor devices are subjected to test and burn-in and it is conventional that the semi-conductor or integrated circuit be packaged before these tests. This has become economically undesirable for semi-conductor manufactures and it is therefore more desirable to test the bare die before packaging. This bare die testing is exemplified in European Patent Application 0 554 622. This publication teaches the use of microbumps, preferably copper spheres soldered to the pads and distributed in a pattern corresponding to the pattern of contact pads of the bare die under test.
U.S. Pat. No. 5,302,891 discloses a two piece reusable burn-in/test fixture for discrete dies and comprises an assembly with one member affording electrical connection to the die and to the test fixture and a second portion for pressing the die against the electrical contacts and holding the same in contact.
U.S. Pat. No. 4,918,513 also discloses a packaging method for mounting an integrated circuit chip on an electronic circuit board and includes a small sized substrate having an electrode pattern disposed on its surface. An IC chip is mounted on the substrate and is connected with the electrode pattern. A mold layer is provided to cover the IC chip and connector pins project from the substrate permitting the carrier to be mounted in a socket on the surface of an electronic circuit board to test the IC device.
The known temporary die carriers are not particularly designed to be compatible with automation equipment. These devices require manual application of force such as hinged components, clamps, screws, etc.
Further, existing methods of establishing temporary electrical connection to the die under tests incorporate wire bonds from the die pad to the temporary package, the use of a temporary connection established by a polyamide film or substrate with metal traces for electrical contact with resilient contacts.
It is better that optical placement of the die on the die interconnect assures correct alignment between the bond pads of the die and the interconnecting electrical contacts and eliminating costly precision wafer dicing required by other mechanical alignment means, such as hard stops and spring force plates.
The method of the present invention utilizes a precise penetration of the die pads by pillars on the wafer which penetrate the aluminum oxide on the die pads and optical placement of the die insures correct alignment. Further, this system does not leave a marred surface on the die which requires additional work prior to the packaging.
The present invention overcomes the disadvantages of existing products by providing a temporary package for bare die which can be loaded and unloaded by precision handling automation equipment.